1. Field of the Invention
This invention relates generally to a waveguide device, and more particularly, to a dielectric aperture assembly which includes a grid-like structure defining a waveguide embedded in a plurality of layers of solid dielectric material to provide an RF signal transmission path through the portions of the solid dielectric layers interior to the waveguide. In addition, this invention describes a method for embedding the grid-like structure in the layers of solid dielectric material.
2. Background Information
It is well known that a waveguide constrains or guides the propagation of electromagnetic waves along a path defined by the physical construction of the guide. In a broad sense, devices such as a pair of parallel wires or a coaxial cable can operate as a waveguide. Normally, however, waveguides usually take the form of a metallic tube operable to confine and guide the propagation of electromagnetic waves in the hollow space interior to the tube. As a general rule, the transmission of an electromagnetic wave through the hollow interior of the waveguide is possible if the wavelength of the electromagnetic wave is less than twice the dimensions of the hollow interior.
Although hollow waveguides and coaxial cables are the most common in application, other types of waveguides are also known. For example, a single conductor has been used as a waveguide, and is referred to as a G-string. Another type of waveguide referred to as a microstrip includes a flat conducting strip having a predetermined spacing from a ground plane. A third type of waveguide formed from a dielectric material has been used for the short-distance transmission of VHF waves, and takes the form of a dielectric rod wherein the propagating wave is partly inside and partly outside the dielectric material.
While each waveguide described above does, in fact, provide an electromagnetic wave or RF signal propagation path through the guide, none of these waveguides is directly operable in conjunction with a structure formed from layered sheets of solid dielectric material to provide an RF signal transmission path through the solid dielectric sheets. Specifically, none of the waveguides described above is arranged to be completely embedded in a solid, multi-layered dielectric structure to provide an RF signal transmission path through the solid body of the structure.
It would be desirable to provide a solid, multi-layered dielectric structure having a waveguide embedded therein since it has been found that solid, multiple dielectric structures, in and of themselves, have many useful applications. For example, multi-layered dielectric structures may be used in phased array antenna systems to form the aperture assembly of each phase control module mounted to the antenna face. If this were the case, any RF signal either launched or received by an individual phase control module would be passed through the solid, multi-layered dielectric aperture assembly. However, without some form of RF conduit such as a waveguide embedded in each phase control module multi-layered dielectric aperture assembly, there is a possibility that a portion of the RF signal passed through an individual aperture assembly will become trapped between adjacent dielectric layers. Not only will trapping a portion of an RF, signal between adjacent dielectric layers in a particular aperture assembly cause an incomplete RF signal to be either launched or received by the associated phase control module, the portion of the RF signal trapped between adjacent dielectric layers in a given aperture asembly may produce RF cross-talk with an adjacent aperture assembly in the array.
Therefore, there is a need for an aperture assembly formed from a waveguide embedded in a solid, multi-layered dielectric structure wherein the waveguide provides an essentially lossless RF signal transmission path through the solid dielectric layers. In addition, there is a need for a method for fabricating a dielectric aperture assembly by embedding a waveguide in a structure formed from multiple layers of solid dielectric material.